A new method for effective parameterization of catchment-scale aquifer through event-scale recession analysis

Accurate estimation of aquifer properties is of critical importance in representing the interactions between hydraulically connected surface-subsurface systems. The variability in recession characteristics (i.e., decline rates and slope nonlinearity) shows that each recession event (RE) occurs under different hydraulic diffusivity conditions between the stream-hillslope. Therefore, the streamflow recession characteristics should be considered in the effective parameterization of the catchment-scale aquifer. This study presents a new method for estimating catchment-scale aquifer properties while accounting for distinct recession characteristics through event-scale recession analysis. In this work, we used the recently developed BE3S (Hong et al., 2020) for (1) explicit incorporation of river stage observations as forcing data to account for the distinct recession characteristics and (2) numerical prediction of outflow from a Boussinesq aquifer to comparatively evaluate analytically derived effective groundwater parameters. We also addressed the relevance of the net subsurface discharge (NSD) observations in event-scale recession analysis for the catchment-scale aquifer parameterization. Specifically, we found that the catchment-scale NSD data plays a role in determining the initial saturated aquifer thickness (Dini) and the size of contributing aquifer (Ac), which varies in individual REs. The applicability of the proposed parameterization scheme was successfully validated for individual REs with distinct recession slopes, demonstrating that hydraulic diffusivity parameters can be estimated by explicitly incorporating recession characteristics. As a catchment-scale application of hydraulic groundwater theory, we expect that the proposed scheme for effective groundwater parameterization will contribute to the accurate representation of the catchment-scale stream-hillslope hydrologic continuum.